Field of the Invention
The present invention relates to mobile communication.
Related Art
3rd generation partnership project (3GPP) long term evolution (LTE) evolved from a universal mobile telecommunications system (UMTS) is introduced as the 3GPP release 8. The 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in a downlink, and uses single carrier-frequency division multiple access (SC-FDMA) in an uplink. The 3GPP LTE employs multiple input multiple output (MIMO) having up to four antennas. In recent years, there is an ongoing discussion on 3GPP LTE-advanced (LTE-A) evolved from the 3GPP LTE.
As disclosed in 3GPP TS 36.211 V10.4.0 (2011-12) “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 10)”, 3GPP LTE/LTE-A may divide the physical channel into a downlink channel, i.e., a physical downlink shared channel (PDSCH) and a physical downlink control channel (PDCCH), and an uplink channel, i.e., a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH).
Meanwhile, in recent years, research into communication between devices or the device and a server without human interaction, that is, without human intervention, that is, machine type communication (MTC) has been actively conducted. The MTC represents a concept in which not a terminal used by human but a machine performs communication by using the existing wireless communication network.
Since MTC has a feature different from communication of a normal UE, a service optimized to MTC may differ from a service optimized to human-to-human communication. In comparison with a current mobile network communication service, MTC can be characterized as a different market scenario, data communication, less costs and efforts, a potentially great number of MTC devices, wide service areas, low traffic for each MTC device, etc.
Recently, it is considered to extend cell coverage of a BS for an MTC device, and various schemes for extending cell coverage are under discussion. However, when the cell coverage is extended, if the BS transmits a downlink channel to the MTC device located in the coverage extension region as if transmitting a downlink channel to a normal UE, the MTC device has difficulty in receiving the channel. Likewise, when the MTC device located in the coverage enhancement region transmits an uplink channel to the BS in a usual way, the BS may have difficulty in receiving the uplink channel. In particular, the BS may have difficulty in receiving a physical random access channel (PRACH) among uplink channels due to characteristics thereof.